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  • #16
    Hi Michael
    Started working with FIR Designer and gotta say: Thanxs for writing the program. It's pretty straight forward and sort of easy to use.
    All's working like a charme so now I only need milage on working with al the stuff in there....

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    • #17
      Hi Timo,

      Thanks very much.

      BTW Version 1.15.1 includes the 1/3rd octave frequency display scaling you asked for. See the Project -> Preferences menu.

      Kind regards,
      Michael
      FIR Designer
      www.eclipseaudio.com.au

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      • #18
        OK great Thanxs.
        edit: works really nice and looks the same to what Smaart tells me so i have to guess a lot less now.
        Last edited by Timo Beckman; 11-23-2016, 05:18 PM.

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        • #19
          I've been having some discussions with Michael about his software via email, and he has been very helpful. He suggested bringing some of the discussion into a public forum so others can participate.

          So one of the points of discussion with Michael was about using Complex or Power based magnitude averaging for smoothing imported traces. I am used to using power based averaging when using smaart to tune a system in situ. I am curious to hear from anyone who thinks complex averaging may be better suited to the needs task of FIR filter design. I am used to looking at power based averages, and when using complex averages and broad bandwidth averages Ive been able to generate so initially counter intuitive results (where a big dip in the mag response appears where there is no dip at a higher resolution).

          I'd also been to hear from Michael about the 'use coherence' function. I assume this uses the coherence value to weight each data point in the smoothing. However, you know what they say about assumptions...

          Best,

          Phillip

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          • #20
            Hi Phillip,

            A number of smoothing/averaging functions in FIR Designer have the option to "Use coherence." Coherence (usually plotted as a function of frequency) is a measure of how reliable each frequency component is, on a scale of 0.0 to 1.0.

            When "Use coherence" is checked, the smoothing/averaging process considers frequency values with a higher coherence score to be more important than frequency components with a low coherence score, and so the smoothed/averaged result will tend closer to the values with high coherence.

            Mathematically, rather than taking a simple average (i.e. summing values and dividing by the number of values), using coherence involves multiplying each frequency component by its coherence value, summing them all up, then dividing by the sum of the coherence scores themselves: essentially weighted averaging.

            Coherence appears in SMAART trace (TRF) files and SysTune overlay (STO) files.

            Kind regards,
            Michael
            FIR Designer
            www.eclipseaudio.com.au

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            • #21
              Michael,

              Thanks. Yep I understand how coherence works in Smaart; I just wanted to make sure my understanding of how that data is used by FIR Designer.

              There are a number of features I'd love to see in the software, and I'm not going to bomb in with all of them immediately, until I have a better grasp of the tool. However I would find a cursor readout for X & Y values, when over any graph quite useful. I know this may be a little more complex than I'd like to imagine on account of some tabs, displaying five or so graphs on the same pane.

              Best,

              Phillip

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              • #22
                Thanks for the suggestions, here and via email. I'll look in them. Just a few thoughts in response to your email.... for everyone here.

                Your suggestion of a strength or % parameter on the Auto Mag and Auto Phase bands is a great idea and fairly easy to code.

                Also, I've been thinking about how to give differing priorities to boosts and cuts in the Auto Mag process. The challenge is defining what is a boost and what is a cut, but I have some ideas that might work.

                Auditioning functionality is something I started on about a year ago but it's not yet complete. Basically WAV file playback with the FIR filter switchable on/off and in the "off" case, ensuring time alignment with the peak of the "on" case.

                Kind regards,
                Michael
                FIR Designer
                www.eclipseaudio.com.au

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                • #23
                  In response to Phillip's suggestions, the latest version 1.24.1 includes measurement smoothing on the Import tab, and the option to do either Complex or Power smoothing on the magnitude - similar to SMAART.

                  Also new are five linear-phase brick-wall crossover filter prototypes; denoted by their length in milliseconds. The longer the length, the sharper the filter. (The filter delay is half the filter length and the stop band is below -100 dB.)

                  Kind regards,
                  Michael
                  FIR Designer
                  www.eclipseaudio.com.au

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                  • #24
                    Thanks for being so responsive Michael.

                    I think it would be useful in the audition functionality to switch between a handful of prototype FIR candidates.

                    I am curious to hear from Michael, or anyone else, what the use cases for the maximum phase filters in the Mag Adjust pane are. I can see the the phase response is opposite of a minimum phase filter with the same parameters (and thus a 1khz 1oct +6dB min phase boost + a 1kHz 1oct +6dB max phase boost, will result in a +12dB linear phase boost), however I am not certain in what particular situations this would be preferable to a minimum or linear phase filter (apart from experimenting and seeing if it tends closer to a flat phase response). Experiences or suggestions?

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                    • #25
                      Hi Phillip,

                      The maximum phase option, on the Mag Adjust tab, mainly came about because it was very easy to implement. (The IR is just the time reverse of the minimum phase IR.) And, as you alluded to, applying maximum phase EQ on a minimum phase response will tend the response towards flat phase and take some of the load off the Phase Adjust tab; if flat phase is the intended result.

                      Kind regards,
                      Michael
                      FIR Designer
                      www.eclipseaudio.com.au

                      Comment


                      • #26
                        Thanks Michael.

                        I've got some FIR's loaded into London Architect now. I notice LA truncates the value of each coefficient to 7 digits (6 decimals), I'm not sure if this is a UI convince, but ought one be concerned about error being introduced via this truncation? I haven't yet had a chance to load this onto a Blu and Smaart the result to see how well it conforms to the trace in FIR designer.

                        It also managed to add a coefficient, so my 400 FIR became 401. Odd.

                        Phillip

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